In a test tube containing a salt, a few drops of dilute H₂SO₄$H_{2}SO_{4}$ was added, which gave colourless vapours having the smell of vinegar. The vapours turned the blue litmus paper red. Identify the correct anion from the following :

Core Logic

Addition of dilute H₂SO₄$H_2SO_4$ to a salt releases a gas. The gas has a "vinegar" smell, which is characteristic of Acetic acid (CH₃COOH$CH_3COOH$). The vapours turn blue litmus red, confirming it is acidic. Reaction: Acetate salt + dil. H₂SO₄ arrow CH₃COOH (vinegar smell)$\text{Acetate salt} + \text{dil. } H_2SO_4 \rightarrow CH_3COOH \text{ (vinegar smell)}$

Step 1: Final Conclusion

The anion present in the salt is Acetate, CH₃COO^-$\mathrm{CH}_3\mathrm{COO}^-$.

Pattern Recognition

Sensory clues in qualitative analysis: Vinegar smell = Acetate. Rotten egg smell = Sulphide. Brisk effervescence (colorless/odorless) = Carbonate.

Chapter Mix

Class 11 Chemistry: Practical Chemistry